There are three ways for you to implement the Word Add-In for you and your organization. 

If your organization allows individual users to install Add-Ins, then installing via the Microsoft AppSource is your best route.

Install via Microsoft AppSource

For an individual, wanting to learn how to install themselves, see also: How do I download the Word Add-On?

If your organization requires tighter authorization, your IT department can use one of the following options.

Install via Microsoft 365 Admin Center

Install via Sharepoint Catalog